Hydraulic pressure devices are efficient at producing high torque from relatively compact units. Their ability to provide low speed and high torque make them adaptable for numerous applications. U.S. Pat. Nos. 4,285,643, 4,357,133, 4,697,997 and U.S. Pat. No. 5,173,043 are examples of hydraulic motors.
Low speed high torque gerotor motors are well represented in agriculture and commercial usages. Examples include scissorlifts, wenches, grain elevators and other applications requiring well controlled remote power. Examples include the U.S. Pat. Nos. 3,572,983, 4,390,329 and 4,480,972. These devices use a powder metal rotating valve in order to connect the expanding and contracting gerotor cells to the pressure and return feeds. One perennial problem with these motors is that they are prone to stall due to the separation of the valve from either the manifold or the balancing ring that biases the rotary valve in contact with the manifold. Over the years, companies such as Eaton have struggled to develop a commercial device which does not present this particular problem. Efforts are continuing within the industry to accomplish this result.
In addition to the above, prior art rotary valve motors have contained powder metal valves which necessitated complicated dies for the manufacturer thereof. In addition, there are inherent manufacturing inaccuracies to this construction, particularly in the main valve drive spline interconnection, which inaccuracies cause timing errors in addition to other problems. In use, the wear between the valve and the balancing ring, cause leakage to occur bypassing the valve, thus significantly reducing the volumetric efficiency of the hydraulic motor.
The valve in the present invention solves these particular problems in an efficient compact easy to manufacture unit.
These prior art units, however, require extensive machining of the housing and include many parts.
The present invention eliminates these problems.